The actor refuses to travel without his beloved Argentinean Mate, which often confuses the authorities - because it looks like a bag of weed.

And it doesn't help that Mortensen, who grew up in Argentina, drinks his tea with a pipe.

He was recently stopped on his way to the Toronto Film Festival in Canada.

He says, "They asked me if it's (pipe) a bong or a pipe to smoke pot. I've made the mistake of putting the mate in a plastic Ziploc bag instead of its original packaging, so that it ends up looking like pot. At first, they (officials) always think the worst, but then you explain to them what it is, and it's always been OK."

Mortensen explains he likes to travel with his own yerba because he finds it difficult to find in local stores around the world.